Glutamate Dehydrogenase (GLDH) Assay Kit

Glutamate dehydrogenase (GLDH) exists in most microbes and in mitochondria of eukaryotes. In mammalian, GLDH is found in many tissues including liver, kidney, heart and brain, but especially in hepatocytes. GLDH is an essential enzyme to synthesize urea and it catalyzes the reversible conversion from glutamate to alpha-ketoglutarate.
Clinically GLDH is a deviation enzyme in blood which deviates from cells when the cells are damaged, only low level of GLDH is found in serum from healthy individuals.
In preclinical toxicity test, ALT in blood has been measured as a marker of liver injury, however, ALT does not change in slight liver injury. Also some reports ALT increase by other causes than liver injury. The combination measuring of GLDH and ALT enable to detect liver injury with higher sensitivity as GLDH is specific biomarker of liver injury.

FDA Recognition of GLDH's Utility

The FDA (Food and Drug Administration) issued the following statement in November 2025, acknowledging the importance of GLDH as a biomarker. (The following is quoted from the Drug Development Tool Qualification.)

The FQP is for serum glutamate dehydrogenase (GLDH), a safety biomarker to be used in clinical trials for participants with elevated serum transaminases due to muscle injury or degeneration when Drug Induced Liver Injury is being considered. GLDH should be used in conjunction with standard hepatic injury monitoring biomarkers (e.g. alanine aminotransferase (ALT), aspartate aminotransferase, gamma-glutamyl transferase (GGT), total bilirubin, and alkaline phosphatase). GLDH has not been studied in patients with preexisting liver disease.

Principle of the GLDH assay

GLDH in the sample catalyzes the conversion of ammonia and α-ketoglutarate to glutamate. During this reaction, NADH is oxidized to NAD⁺, resulting in a decrease in absorbance at 340 nm. The GLDH level is determined by measuring this decrease in absorbance.

Figure 1. Principle of the GLDH assay

LabAssay™ GLDH (AA-type) is a research reagent for measuring GLDH for use with automated analyzer in samples. GLDH levels in samples can be measured quickly.

Examples of measurement

Correlation with the Previous Version of the Kit

GLDH levels in rat serum and plasma were measured using LabAssay™ GLDH (AA-type) (hereinafter, this assay kit) and LabAssay™ GLDH-Rat (A-type) (Code No. 291-93401, hereinafter, the previous kit), and the correlation between the two products was evaluated.

[Result]
A strong correlation was confirmed between the measurements obtained using the current and previous kit.

Correlation with products from other manufacturers

GLDH levels in serum and plasma from humans, mice, rats, dogs, and rabbits were measured using LabAssay™ GLDH (AA-type) (hereinafter, this assay kit) and assay reagents from Company A and Company B. The correlations between the measurement results of each product were evaluated.

[Result]
A strong correlation was confirmed between the values obtained with LabAssay™ GLDH (AA-type) and those obtained using products from other manufacturers.